gridview1里面DropDownList报错

Question

 protected void gridview1_RowEditing(object sender, GridViewEditEventArgs e)
        {
            this.gridview1.EditIndex = e.NewEditIndex;
            DropDownList ddl = (DropDownList)this.gridview1.Rows[e.NewEditIndex].Cells[2].FindControl("ddlUpBigtype");
            ddl.DataSource = this.bllBig.GetBigtype("");  //未将对象引用设置到对象的实例。***这里报错是为什么啊??要怎么写啊这里?            ddl.DataValueField = "bigtypeid";
            ddl.DataTextField = "typename";
            ddl.DataBind();
            ddl.SelectedValue = this.gridview1.Rows[e.NewEditIndex].Cells[0].Text;
            Bind();
        }

Answer 1

应该放在RowDataBound事件中
    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            DropDownList ddl = (DropDownList)e.Row.Cells[2].FindControl("ddlUpBigtype");
            if(ddl!=null) 
            {   
                ddl.DataValueField = "bigtypeid";
                ddl.DataTextField = "typename";
                ddl.DataBind();
                ddl.SelectedValue = this.gridview1.Rows[e.NewEditIndex].Cells[0].Text;
                Bind();
            }        }
    }

Answer 2

楼上正解．DropDownList ddl = (DropDownList)this.gridview1.Rows[e.NewEditIndex].Cells[2].FindControl("ddlUpBigtype");
　
因为没有找到DropDownList类型，所以ddl为空，空的话当然就不能给他赋值了，我也经常遇到这种错误．也有可能是this.gridview1.Rows[e.NewEditIndex].Cells[2]这里没有DropDownList控件，Cells[2]表示GridView的第三列，看看是不是放错了．呵呵． protected void gridview1_RowEditing(object sender, GridViewEditEventArgs e)
        {
            this.gridview1.EditIndex = e.NewEditIndex;
　　　　　　　if(this.gridview1.Rows[e.NewEditIndex].Cells[2].FindControl("ddlUpBigtype")!="")
            {
            DropDownList ddl = (DropDownList)this.gridview1.Rows[e.NewEditIndex].Cells[2].FindControl("ddlUpBigtype");
            ddl.DataSource = this.bllBig.GetBigtype("");  //未将对象引用设置到对象的实例。***这里报错是为什么啊??要怎么写啊这里?            ddl.DataValueField = "bigtypeid";
            ddl.DataTextField = "typename";
            ddl.DataBind();
            ddl.SelectedValue = this.gridview1.Rows[e.NewEditIndex].Cells[0].Text;
            }//就不会出错了
            Bind();
        }

Answer 3

ddl.SelectedValue = this.gridview1.Rows[e.NewEditIndex].Cells[0].Text;
//GridView1_RowDataBound里面没有e.NewEditIndex,我要怎么获取默认值呢

Answer 4

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e) 
    {         if (e.Row.RowType == DataControlRowType.DataRow) 
        { 
            DropDownList ddl = (DropDownList)e.Row.Cells[2].FindControl("ddlUpBigtype"); 
            if(ddl!=null) 
            {  
                ddl.DataValueField = "bigtypeid"; 
                ddl.DataTextField = "typename"; 
                ddl.DataBind(); 
                ddl.SelectedValue = this.gridview1.Rows[e.NewEditIndex].Cells[0].Text; //一楼的这里有问题啊
                Bind(); 
            } 
        } 
    }
我点编辑按钮后,里面的DropDownList 绑定后默认是选中的第一个值,我要怎么让他默认选择的是我点编辑的时候传过来的值